Automatic transmitter



Feb. 16, 1932. J. L. FINCH 1,844,950

AUTOIATIC TRANSMITTER Filed May 21, 1929 2 Sheets-Sheet 1 INVENTOR JAMES L. FINCN BY w AITORNEY Feb. 16, 1932. J. L. FINCH 4,

AUTOMATIC TRANSMITTER Filed. may 21, 1929 2 Sheets-Sheet 2 INVENTQR JAMES L FINCH ATTORNEY Lil Patented Feb. 16, 1932 UNITED STATES PATENT OFFICE JAMES L. FINCH, OF ROCKY POINT, NEW YORK, ASSIGNOR TO RADIO CORPORATION 01' AMERICA, A CORPORATION OF DELAWARE AUTOMATIC TRANSMITTER Application filed May 21,

This invention relates to an automatic transmitter and has for one of its objects the provision of a new and useful method and means for transmitting signals.

In order to produce electrical signals in a telegraphic line or in an antenna, there is often employed what is known as an automatic transmitter in which a tape has perforations or holes punched therein corresponding to signal characters to be transmitted. It has been customary to use a device with mechanical fingers, actuated by gears and earns, to pass through the holes in this tape and to so efi'ect other parts of the mechanism as to close and open electrical contacts in accordance with the desired signal.

The use of such a mechanical device necessarily limits the speed at which signals may be formed reliably on account of the inertia of the reciprocating moving parts. One object of this invention is to provide a transmitting system similar in character to those already in use which minimizes the number of moving parts and which eliminates all reciprocating parts so as to remove the elements which in the past have limited the speeds obtainable.

Further, in telegraphy, it is desirable that the signal characters should be formed with great precision of regularity. Other devices now in use or proposed have been capable of very high speeds but have lacked this precision. A notable example is one which employs a tape ofinsulating material along which slits are cut and which passes between two electrodes across which a high potential is impressed. In that case when a slit in the tape comes between the electrodes a discharge takes place between them through the slit and the resulting current is used to form the signals. \Vhen the slit passes the electrodes. current is interrupted and the signal character is ended. This cannot be depended upon to give any great precision in startiug and ending signal characters. My present invention provides a method and means for overcoming these defects, giving the required precision.

Further, it is desirable to employ in any 1929. Serial No. 864,531.

new device, as much of the equipment already in use in the apparatus bein replaced, as possible, so as to avoid expen iture for new equipment. Accordingly, my invention is so arranged as to employ the same machine for punching the tape used in connection with automatic transmitters as is now in general use.

It has also been found desirable at times to vary the lengths of signal characters, but in the ty es of apparatus already in use, this is excee ingly difficult to do, the length of characters being fixed by construction of the device. Another object of this invention is to provide a method and means whereby the lengths of signal characters are made substantially independent of the transmitter tape punchings- The means for putting into effect the foregoing object takes the form of a generator peculiarly adapted for this invention, in which potentials are generated solely at times when signal characters are to be transmitted, the potentials generated, acting to control electrically, for example a. radiating transmitter, it signalling is to be done by means of electromagnetic waves.

In order to have purely electrical control of the radiating antenna, thereby dispensing with slow acting mechanical relays another object of this invention is to provide an electrical circuit having two points of electrical stability wherein at one of its points of stability it acts to cause energization of, for example, a transmitting antenna and wherein at its other position of electrical stability causes complete decnergization of the radiating antenna In accordance with the practice of the United States Patent Oflice the novel features of this invention are set out in the appended claims. The mode of operation togather with ways in which the invention may be structurally carried out, may best be understood by referring to the accompanying drawings in which:

Figure 1 diagrammatically illustrates a tape transmitter built in accordance with the principles of this invention,

Figure 2 illustrates the phase relations of potentials generated to control signalling or working current in a telegraph line or a transmitting antenna in accordance with signals punched on a transmitting tape,

Figure 3 illustrates diagrammatically and partly in section, apparatus for generating potentials illustrated in Figure 2,

Fi re 4 is a view of the apparatus disclose in Figure 3 taken on line 4, 4 of Figure 3, and

Figure 5 is a graph illustrating the action of the apparatus at C in Figure 1.

Turning to Figure 1 there is illustrated at A a tape having signal characters punched therein and generators for generating potential corresponding to the beginnings and endin of si nal characters. The upper row of ho es in t e tape begins characters whereas the lower rows of holes ends characters. The middle row of holes are solely for traction pur oses.

e potentials generated at A for beginnings and endin s of signal characters become efl'ective at3 for controlling the sending of a tone over a land line to, for example, a transmitter at point D. Ordinarily when a tone is sent out on the land line it is rectified at a transmitter such as the one at D and the rectified current causes energizetion of the antenna. For reverse signalling presence of a tone in the land line causes deenergization of the antenna at D- The current sent over the land line or the current in the antenna may be considered either as signalling currents, or. in a more general sense they may be considered simply as working currents In the case of wired telegraphy, currents sent over the land line would be utilized in one of a number of ways at a receiving point such as D.

In order to control the transmission of the working currents by means of the otentials generated at A there is provide at C means for electrically controlling the working currents. The apparatus at C takes the place of undesirable mechanical relays.

As shown, the apparatus at C comprises electron discharge devices having their anodes and their control electrodes cross connected or intercoupled in a manner such that the apparatus has two points or degrees of electrical stability. That is to say, there is either a predetermined maximum anode current flow in one of the electron discharge devices and a predetermined minimum anode current flow in the other of said electron discharge devices or the reverse. The change is controlled by potentials ap lied to the input terminals of the devices, in this case those enerated at A, and the change is very rapidly accomplished.

By utilizing the current flow through one of the devices the energization of the antenna D through the intermediary of the apparatus at B may be readily controlled.

More particularly I have shown at A a tape- 1 which is driven by means of a motor 2, star wheel 3, and center holes 4 past an electrode 5. The upper row of holes 6, in the tape, indicate the beginnings of signal characters, and the lower row 8 indicates the ends of signal characters.

Generator 10 generates an alternating potential having a wave form shown in Figure 2 at a, the sharp positive peaks bein efiective for the commencement of signal c aracters. Similarly generator 12 generates potentials such as shown in Figure 2 at b, for ending signal characters. These generators, are driven through a suitable gear ratio and have such a number of poles so as to give one-half cycle for each Morse unit of the tape, where a Morse unit corresponds to half of the spacing between signal perforations along one side of the tape when a continuous row of dots is being formed.

Potentials having the wave forms shown in Figure 2 may be generated by rotating a properly shaped metallic rotor past field poles. In Figure 4, the poles 200 may be energized by a steady current flowing through pick up coils 202 or by separate magnetizing coils. When straight portions 204 of the rotor move by the poles, the flux linking therethrough increase suddenly causing the positive peaks shown in Figure 2. Portions 206 of the rotors are so shaped that the flux through the poles uniformly decreases, as they pass by. thus giving the flat portion 0 of the potential wave generate Only the positive peaks of the voltages generated are utiltized for controlling the energization at D. The relative phase relations of these positive peaks may be varied by the apparatus shown in Figures 8 and 4.

The generators have their rotors 14, 16 mounted on a common shaft 18 and may be insulated from each other by the interposition of a suitable insulator 20.

The stators are mounted on curved base plates 22 and held thereby by means of straps 24 which. however, allow rotation of the stators. By means of gear segment 26 and screw 28 the stators may be rotated relative to the rotors. Pointers 30 and scales 32 may be utilized for indicating the relative phase of the positive peaks generated.

As shown in Figure 2 the times of the generation of peaks may be varied, by means of the mechanism just described, as indicated bv the dotted lines. In this way the lengths of signal characters may be varied, that 1s to say, the lengths of time at which current flows, in-the land lines 40, for, for example, controlling the energization of the radiating antenna. may be varied within suitable limits. In this manner the energization of the antenna becomes almost independent of tape perforation variations, for the energization of the antenna may be made to vary within one half the diameter of a signal perforation in tape 1.

In the apparatus at B there is disclosed a tone generator 34 coupled to a pair of electron discharge devices 36, 38 connected in push-pull fashion. The tendency of generator 34 would be to send a tone or alternating current continuously overland line 40. However. by suitably biasing the control electrodes of electron discharge devices 36, 38 relative to their cathodes, no tone or signal will appear on land line 40.

The apparatus for controlling the control electrode bias of electron discharge devices 36, 38 is illustrated at C. At C a pair of electron discharge devices 42, 44 have their anodes and control electrodes resistively cross or interconnected through resistances 46, 48. 50 and 52. A suitable. source of anode potential 54 and another source 56 for suitably biasing the control electrodes of electron discharge devices 42, 44 are provided. The electron discharge devices and the various resistances utilized are so chosen that the circuit is made symmetrical.

Because of the symmetrical arrangement there may be a time at which the same value of anode current flows throu h both tubes. This corresponds to point 0, see Figure 5). However, this point Is one of great instability for. assuming the case just described, and assuming due to some external or internal change, a slight increase in anode current through resistance 46, thus to point 0 it will be apparent that there will be an added negative potential on the control electrode of electron discharge device 42. Because of the increase in negative bias of the control electron discharge device 42, its )late current will become less and accordingly because of the manner in which the control electrode of tube 44 is connected to the plate circuit of tube 42, the grid of tube 44 will become more positive. Due to the last change, increased current flows through resistance 46 thereby making the grid of tube 42 still more negative. This action will continue until tube 42 blocks and a maximum current flows through tube 44. This state of affairs is one point of electrical stability and is illustrated in Figure 5 by points 0" and 0" where O" indicates tube 42 blocking and 0'' indicates a predetermined maximum current flow through tube 44.

By the addition of a positive potential on the grid of tube 42 sufiicient to carry it past the point 0 of electrical instability, it will be seen that an action similar to the one already described will result in the blocking of tube 1-4 and a maximum anode current flow through tube 42. This corresponds to points P and P, Figure 5.

The apparatus will tend to stay in either of two positions of electrical stability, either (7), 0" or P and P, for, assuming point P to-be moved to point P" by some applied potential, as soon as that potential is removed, P" will slide back to P. The only way to change from one position of electrical stability to the other is then, the application of a potential sufficient to carry the point P, sa past the point 0 of unstable equilibrium. :1 connection with the apparatus at C, it is to be noted that resistances 50 and 52 may be replaced bysuitable potential sources, and that resistances X and Y are not absolutely necessary. As a matter of fact, it can be seen that it is possible, by suitabl choosing and desi ning the apparatus at that resistances Y 50 and 52 may me dispensed Now, turnin to the apparatus at A, it will be seen that wdxen a perforation is between brush 58 and electrode 5 and by suitably synchronizing the rotation of the generators 10, 12 with the rotation of the star wheel which controls the passage of tape 1 over electrode 5, a positive potential will be generated by generator 10 at the time when a perforation is under brush 58 causing a current flow through resistance 60. This positive potential will be of suflicient magnitude to cause a disruptive discharge through the air through the perforation so no actual contact between 58 (or 62) and 5 is required. This current flow is made of sutficient value such that the voltage drop across resistance 60 overcomes the negative bias on the grid of tube 44 bringing it past the point of electrical instability and thereby causing the action already described wherein tube 44 becomes conductive and tube 42 blocks.

When tube 42 blocks there is no anode current flowing through resistance 48 and because there is no voltage dro across resistance 48 at that time, tones rom generator 34 are sent over line 40 to the apparatus at D. These tones when rectified may control a low power amplifier at D allowing of the passage of oscillations into a high power amplifier and thereby allowing the radiation of energy to indicate a signal character. For reverse keying, of course, the tone could, in a sgnilar manner be utilized to stop radiation at When a perforation indicating the end of a signal character passes underneath brush 62, a potential will, at that instant, be generated by generator 12 causing current to flow through resistance 64. This carries the potential on the control electrode of tube 42 past the potential corresponding to electrical instability which in turn will cause full current to flow in the anode circuit of tube 42 and the blocking of tube 44.

When full current flows in the anode circuit of tube 42 there is a large voltage drop across resistance 48 in the anode circuit thereof which makes the control electrodes of tubes 36, 38 highly negative causing them to block. Hence no tone will be sent over land line 40 and accordingly the antenna may be deener zed or ener ized as desired.

As s own at A a ct corresponds to a pair of holes unched directly opposite one another. T ey are punched in this manner due to mechanical simplicity in the punching apgaratus. ACCOI'dIIflY the brushes 58, 62

ave been stagger-e in such a manner that the two holes representing a dot can become eflective in starting and ending a dot character. If a dash is to be punched in the tape the otherwise ending dot hole is not punched and, although there is a potential generated at 12 at a time when ordinarily a dot would be ended, it does not become efiective in turning oil the transmitter because of the dielectric strength of the tape 1 which prevents a disruptive discharge to electrode 5.

The tone sent over the land line 40 to the low power amplifier at D may be used in any desired way for either direct reception, relaying or for controlling radiation; in the last instance, for example, the rectified tone may be used to either control the grid bias or plate volta e on one or more stages of the low power amrfiifier in a manner such that when tone is present there is a high frequency output from the low power amplifier. For reverse keying, of course, the reverse is made true.

The advanta es of this invention although pointed out briefly hereinbefore may h repeated more specifically here. By providing apparatus to vary the relative phase of the peak voltages generated by generators 10 and 12 the lengths, or bias of signal characters may be varied as desired thus compensating any characteristics of control lines or other circuits which may tend to lengthen or shorten characters. Because of the elimination of mechanical relays for controlling the transmitter, high speeds of transmission can be realized, for the action of the electrical circuits at C is practically instantaneous.

By generating voltages at 10 solely at time when a Morse character may start, flashovers through perforations other than the one intended are obviated; and, because of the substantial independence of the generation of the voltages relative to the hole punchings on the tape, wide variations in the punched tape, that is to say, as much as a punching one-half its diameter out of place, will not affect the tranmitted signal. A punching one-half of one diameter askew is, in this art, an extreme variation; and hence, it will be seen that this invention is a decided improvement over automatictransmitters heretofore .utilized.

Various minor changes, as will be apparent to one skilled in the art, may be made throughout and accordingly the invention is not to be limited by what has been specifineupuo cally described, but only by the scope of the ap nded claims.

aving thus described my invention what I claim is:

l. The method of signalling, which includes, producing a current flow at the beginning of a signal character; utilizing that current flow to afiect the flow of an alternating signalling current; producing another current flow at the end of a signal character, and utilizing the last mentioned How to alfect the flow of said 'alternatin signalling current in a manner different mm the manner in which it was affected at the beginning of a signal character.

2. The method of signalling, which includes, producing a current flow at the beginning of a signal character, electrically utilizing that current flow to affect the flow of an alternating signalling current, producin another current flow at the end of a signa character, and electrically utilizin the last mentioned flow to affect the flow 0 said alternatin signalling current in a manner difi'erent tom the manner in which it was afiected at the beginning of a signal character.

3. The method of signalling, which includes, producing a current flow at the be 'nning of a signal character, utilizing that ow to turn on or oil an alternating signalling current, producing another current flow at the end of a signal character, and utilizing the last mentioned flow to turn ofi or on the flow of said alternating si nalling current.

4. The method of slgna ling, which includes, reducing a current flow at the be inning of a signal character, utilizing that ow to turn on or oif solely electrically a signalling current, froducing another current flow at the en of a signal character, and utilizin solely electrically the last mentioned ow to turn of! or on the fiow of said signalling current.

5. The method of operating a tape transmitter which utilizes a tape havin holes therein for beginning and ending 0 signal characters which includes, generating a potential solely at the time when a hole in the tape is to be efiective in beginning or ending a character, and utilizing the potential so generated to control an alternating signalling current.

6. The method of operating a tape transmitter which utilizes a tape having holes therein for beginning and ending signal characters which includes, generating a potential solely at the time when a hole in the tape is to be efi'ective in beginnin or ending a character, and utilizing sole y electrically the potential so generated to control a signalling current.

7. The method of operating a tape transmitter, which utilizes tape having holes therein for the beginning and ending of signal characters, which includes, enerating a potenial solely at a time when a hole is to be effective for the beginning or ending of a character and utilizing the potential so generated to turn on or off an alternating signallinlg current.

8. he method of operating a ta e trans mitter which utilizes tape having ho es therein for the beginning and endings of characters, which includes, generating a potential solely at a time when a hole is to be efiective for beginning or ending a character and utilizing electrically the potential generated to turn on or off an alternating signalling current.

9. In combination, means for producing a current flow at the beginning of a signal character, means for utilizing solely electrically that current flow to effect the flow of an alternating signalling current, means for producing another current flow at the end of a signal character, and means for utilizing solely electrically the last mentioned flow to affect the flow of said alternating signalling current in a manner different from the manner in which it was affected at the beginning of a si al character. s

10. n a tape transmitter utilizing a tape havin holes therein spaced multiples of a unit istance apart for beginning and ending signal characters, means for generating a relatively high potential solely at times corresponding to the unit spacing and of a value to cause a discharge through a hole in the tape when a hole in the tape is to be effective in beginning or ending a character, and means for utilizing the discharge to control a signalling current.

11. In a tape transmitter utilizing a tape having holes therein for beginning and ending signal characters, means for enerating a potential solely at a time when a ole in the tape is to be efl'ective in beginning or ending a character, and means for utilizing solely electrically the potential so generated to vary an alternating signalling current.

12. In a tape transmitter, utilizing tape having holes therein for the beginnings and endings of signal characters, means for generating a potential solely at a time when a hole is to be effective for the beginning or ending of a character, and means for utilizin the potential so generated to turn on or o a signalling current.

13. In a tape transmitter utilizing tape having holes therein for the beginnings and endings of characters, means for generating a otential solely at a time when a hole is to be effective for beginning or ending a character and means for utilizing solely electrically the potential so generated to turn on or oil a signalling current.

14. An electric circuit having a plurality of degreesof electrical stability, which comprises, a plurality of electron discharge devices, the control electrode of one of said devices being coupled to the anode of another of said devices, and the anode of said last mentioned device coupled to the control electrode of said first mentioned device whereby an increase in current in the anode circuit of one of said devices causes a decrease of current in the other of said devices.

15. An electric circuit having a plurality of degrees of electrical stability, which comprises, a plurality of electron dischar e de vices, the control electrode of one of said devices connected to the anode of another of said devices, and the anode of one of said devices coupled to the control electrode of another of said devices whereby an increase in current in the anode circuit of one of said devices causes a decrease of current in tne other of said devices until blocking occurs in said last mentioned device.

16. In combination, a pair of electron discharge devices having their anodes and control electrodes resistively interconnected, whereby when there is a predetermined maximum anode current in one of "said devices there is a predetermined minimum current flowin in the anode circuit of the other of said evices and means for establishing a reverse state of anode currents in said devices.

17. In combination, a tape having holes nator causes a maximum anode current flow in one electron discharge device, and a minimum anode current in the other electron discharge device, and the other alternator causes a reverse anode current flow in said electron discharge devices, a resistance in the anode circuit of one of said electron discharge devices and connections from said resistance to another electron discharge device for controlling the bias on said last mentioned electron discharge device according to the anode 1 current flow through said resistances.

18. In combination, a tape having holes therein representing the beginnings and endings of signal characters, contact brushes contacting with one surface of said ta e and facing an electrode when a signalling ole in said tape comes under one of said brushes, alternators for generating potentials solely when said brushes face said electrode, a air of electron discharge devices having t eir anodes and control electrodes resistively interconnected, adapted to be affected by the potentials generated by said alternators so that one alternator causes a maximum anode current flow in one electron discharge device, and a minimum anode current in the other electron discharge device, and the other alternator causes a reverseanode current flow in said devices, a resistance in the anode circuit of one of said electron discharge devices and connections from said resistance for utilizing the voltage drop thereacross.

19. In a transmitter utilizing a tape having holes therein for the befginnmgs and endings of characters, means or generating p:- tentials solely at times when a hole is to come efi'ective in the beginning or ending of a character, means for adjusting the relative times at which said potentials are generated, and means for utilizing the potentials so generated to control a signalling current.

20. In a transmitter utilizing a tape having holes therein for the beginnings and endings of characters, means for generating potentials solel at times when a hole is to become effective in the be innin or ending of a character, means 0 era Is in ependently of the holes in the tape or adjusting the relative times at which said potentials are generated, and means for utilizing the potentials so generated to control a signalling current.

21. In an automatic transmitter utilizing a tape having holes therein corresponding to signal characters the method of signalling which includes causing a disruptive space discharge through the holes in the tape when they are to become efiective for signalling and utilizing the disruptive discharges for controlling a signalling current.

22. The method of signalling with an automatic transmitter utilizing a tape, having perforations therein correspondin to signal characters, travelling between a p urality of electrodes which includes causing disru tive space discharges between a pair of t e electrodes when perforations are therebetween, and utilizing the discharges to control the flow of a signalling current.

23. The method of signalling with an automatic transmitter utilizing a tape, having perforations therein corresponding to beginnings and endings of signal characters, travelling between a plurality of electrodes which includes causin disruptive discharges between a pair of t e electrodes at times when the characters are to be started or ended and utilizing the disruptive discharges for controlling the flow of a signalling current.

24. In an automatic transmitter utilizing a tape having signal perforations therein, means for causing signalling current flows corresponding to the perforations in the tape, and means independent of the perforations in the tape for varying within predetermined limits the times at which the signallin currents flow.

25. 11 an automatic transmitter utilizing a tape having holes punched therein corresponding to the beginnings signal c aracters, means 0 ruptive discharge through the tape when a ho e is to become effective in starting or ending a signal character, and means for varying the time at which the discharge occurs.

26. In an automatic transmitter utilizin a tape having signal characters punch therein, means for causin disruptive discharges through the pane i'ngs when they are to become eiiective for si alling, and means for varying, independilitl of the punchings, the times at which the isruptive discharges occur.

27. In a system of the character described, ap aratus having two degrees of electrical sta ility comprising a pair of electron discharge devices each having an hermetically sealed container wherein are contained an electron emitting cathode an anode and a grid, a circuit connecting the grids to ther, means for subjecting the grids throng said circuit to a suitable polarizing otential, a resistance in series with the ano e of one of said devices, a resistance in series with the anode of the other of said devices, a source of anode (potential connected to a point between sai resistances, a resistance connecting the grid of one of said devices to the anode of the other device, and, another resistance connecting the grid of the other device to the anode of said one device.

28. In a system of the character described. apparatus having a plurality of degrees of electrical stability comprisin a pair of electron discharge devices each liavmg an electron discharge device wherein are contained an electron emitting cathode an anode and a control rid, resistances connecting the grids toget er, a source of potential connected between said resistances and the cathodes of said devices, resistive connections connecting the anodes of said devices to-' gether, a source of anode potential connected between the cathodes and the resistive connections connecting said anodes together, a resistance connected from one of the grids of one of said devices to the anode of another of said devices, and, a resistance connected from the grid of said other device to the anode of said one device.

29. In a system of the character described, apparatus having a plurality of degrees of electrical stability comprising a pair of electron discharge devices each having an hermetically sealed container wherein are contained an electron emitting cathode, a cold electrode and a control grid, a circuit connecting the grids together, means connected to a point intermediate said circuit and said and endings of r causing a'discathodes for suitably polarizing the grids of said devices, a circuit connecting said cold electrodes together, means for suitably polarizing said cold electrodes through said cold electrode connecting circuit, a resistance connected from the grid of one of said devices to a cold electrode of another of said devices, and, a resistance connected from the grid of said other device to a cold electrode of said one device.

30. In combination, a source of signalling current, a device, comprising a plurality of electron discharge devices having their control electrodes and anodes purely resistively interconnected, having two conditions of electrical stability coupled to the source of signalling current, changing from one condition of stability to another upon a predetermined flow of signalling current, and a transmitter, responsive for transmission to the changes in condition of said device, coupled to said device.

JAMES L. FINCH.

cathodes for suitably polarizing the grids of said devices, a circuit connecting said cold electrodes together, means for suitably polarizing said cold electrodes through said cold electrode connecting circuit, a resistance connected from the grid of one of said devices to a cold electrode of another of said devices, and, a resistance connected from the grid of said other device to a cold electrode of said one device.

30. In combination, a source of signalling current, a device, comprising a plurality of electron discharge devices having their control electrodes and anodes purely resistively interconnected, having two conditions of electrical stability coupled to the source of signalling current, changing from one condition of stability to another upon a predetermined flow of si alling current, and a transmitter, responsive for transmission to the changes in condition of said device, coupled to said device.

JAMES L. FINCH.

comprises, a plurality of electron discharge DISCLAIMER 1,844,950.James L. Finch, Rocky Point, N. Y. AUTOMATIC TRANSMITTER. Patent dated February 16, 1932. Disclaimer filed July 18, 1934, by the 'assignee, Radio Corporation of America.

Hereby enters this disclaimer to that part of the claims in said specification which is in the followin words, to wit:

14. An electric clrcuit having a plurality of degrees of electrical stability, which comprises, a pluralit of electron dlscharge devices, the control electrode of one of said devices being coup ed to the anode of another of said devices, and the anode of said last mentioned device coupled to the control electrode of said first mentioned device whereby an increase in current in the anode circuit of one of said devices causes a decrease of current in the other of said devices.

15. An electric circuit having a plurality of degrees of electrical stability, which devices, the control electrode of one of said devices connected to the anode of another of said devices, and the anode of one of said devices coupled to the control electrode of another of said devices whereby an increase in current m the anode circuit of one of said devices causes a decrease of ciurrent in the other of said devices until blocking occurs in said last mentioned evice.

[Qfiicial Gazette Augustfll, 1984.1

DISCLAIMER 1,844,950.James L. Finch, Rocky Point, N. Y. AUTOMATIC TRANSMITTER. Patent dated February 16, 1932. Disclaimer filed July 18, 1934, by the 'assignee, Radio Corporation of America. Hereby enters this disclaimer to that part of the claims in said specification which is in the follo words, to wit:

14.An electric circuit having a plurality of degrees of electrical stability, which comprises, a pluralit of electron discharge devices, the control electrode of one of said devices being coup ed to the anode of another of said devices, and the anode of said last mentioned device coupled to the control electrode of said first mentioned device whereby an increase in current in the anode circuit of one of said devices causes a decrease of current in the other of said devices.

15. An electric circuit having a plurality of degrees of electrical stability, which comprises, a plurality of electron discharge devices, the control electrode of one of said devices connected to the anode of another of said devices, and the anode of one of said devices coupled to the control electrode of another of said devices whereby an increase in current in the anode circuit of one of said devices causes a decrease of current in the other of said devices until blocking occurs in said last mentioned device.

{Qficial Gazette August 21, 1934.] 

